Feng Q L, Wu J, Chen G Q, Cui F Z, Kim T N, Kim J O
Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
J Biomed Mater Res. 2000 Dec 15;52(4):662-8. doi: 10.1002/1097-4636(20001215)52:4<662::aid-jbm10>3.0.co;2-3.
To investigate the mechanism of inhibition of silver ions on microorganisms, two strains of bacteria, namely Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), were treated with AgNO(3) and studied using combined electron microscopy and X-ray microanalysis. Similar morphological changes occurred in both E. coli and S. aureus cells after Ag(+) treatment. The cytoplasm membrane detached from the cell wall. A remarkable electron-light region appeared in the center of the cells, which contained condensed deoxyribonucleic acid (DNA) molecules. There are many small electron-dense granules either surrounding the cell wall or depositing inside the cells. The existence of elements of silver and sulfur in the electron-dense granules and cytoplasm detected by X-ray microanalysis suggested the antibacterial mechanism of silver: DNA lost its replication ability and the protein became inactivated after Ag(+) treatment. The slighter morphological changes of S. aureus compared with E. coli recommended a defense system of S. aureus against the inhibitory effects of Ag(+) ions.
为研究银离子对微生物的抑制机制，用硝酸银处理革兰氏阴性大肠杆菌（E. coli）和革兰氏阳性金黄色葡萄球菌（S. aureus）这两种细菌，并结合电子显微镜和X射线微分析进行研究。银离子处理后，大肠杆菌和金黄色葡萄球菌细胞均出现相似的形态变化。细胞质膜与细胞壁分离。细胞中央出现一个明显的电子透亮区，其中含有浓缩的脱氧核糖核酸（DNA）分子。细胞壁周围或细胞内有许多小的电子致密颗粒沉积。X射线微分析检测到电子致密颗粒和细胞质中存在银和硫元素，提示银的抗菌机制为：银离子处理后，DNA失去复制能力，蛋白质失活。与大肠杆菌相比，金黄色葡萄球菌的形态变化较小，提示金黄色葡萄球菌对银离子的抑制作用存在防御系统。
